Kinematic Azimuth Alignment of INS using GPS Velocity Information

A. O. Salycheva and M.E. Cannon

Abstract:	The combination of the Global Positioning System (GPS) and an Inertial Navigation System (INS) can deliver a system performance that is superior to either one in standalone mode, since each system compensates for the other’s shortcomings. Due to large errors of the inertial sensors, error estimation and further compensation have to be performed using external information from GPS. The azimuth misalignment angle, being one of the largest non-stationary INS error components, has a significant impact on the INS accuracy; therefore this paper is focused on the development and testing of a special procedure for the azimuth error estimation. The method presented is based on a traditional Kalman filter and uses GPS velocity and heading information for measurement updates. The filter is divided into two stages, defined by a different degree of observability of the error components in the state vector. The estimation of the azimuth misalignment is performed only when it is strongly observable, in other words, during high vehicle dynamics. To reduce the transition period of its estimation, the problem statement is reformulated so that the azimuth misalignment error becomes a directly measured component. The discussed algorithm is tested for land navigation applications. The results show that precise azimuth error estimation using the proposed approach can significantly improve the INS accuracy in general and the prediction accuracy in particular, when the GPS measurements are not available.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	1103 - 1113
Cite this article:	Salycheva, A. O., Cannon, M.E., "Kinematic Azimuth Alignment of INS using GPS Velocity Information," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 1103-1113.
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